Heating apparatus provided with ovens



Dec. 23, 1941. N. A. HALLSTRM HEATING APPARATUS PROVDED WITH OVENS Filed Dec. 13, 1938 INVENTOR v Jm ATTORNEY Patented Dec. 23, 1941 &266353 HEATING APPARA'EU O-VENS s; PROVIDED' WITH Nils August Ivan Hallstrm', Stockholm Sweden, assignor to Svenska Aktieboia-get Gasaccumwlator, Stockholm, Sweden, a;` eorporati'on of Sweden Application December 13, 1938, Serial No. 245,496 In SwedenDecember 14, 1937 speed' in this. case by one or more bafiies or the 4 Glams;

My invention relates toimprovementsin heating apparatus such as cooking. stoves provided with ovens. More specially the invention. relates to apparatus of this kind in which heat is transmitted from a heat generator to the ovens by means of air or other gas circulating in one or more closed circuts and. has for its purpose to provide for a high circulation speed of the air or gas and as a consequence thereof a high heat transmission. This is. obtained by conveying the air or gas in such a Way as to prevent, at least to, a certain extent, the temperature of the air or gas from being decreased when flowing upwards. Apparatus of this kind hitherto known are usually provided with a circulaton channel, surrounding the ovens and branching off between them. In this way vertical circulation Channels, closed at the sides, and' of the height' of one oven only, have been obtained one above the other., and the temperature of the air ascending in the upper of these channels is d'ecreased by cooled air coming in from the space between the ovens. The diierence in pressure in the channelt has then been too low to produce suflicientl'y high circulation speed through thermo-circulation only. It has therefore been suggested to place the ovens close. to each other, so as to obtain continuous Vertical circulation' Channels; closed' at the sides, and: of a height equal" to the total height of all' the ovens. Through* this-arrangement, high circulation speed has' been attained but, the bottoms and tops of' the ovens, which touch each other, have not received` suffcient heat. In order to overcome this disadvantage it has been suggested to convey the circulating gas through perforations in the bottoms and tops of the ovens. In this way, however, too great resistance to circulation is produced', which will also be dependent upon the size of the objects contained in the ovens'.

One object of theinvention is to avoid these disadvantages. This result is accomplished' by the provision of a circulaton channel' having a vertical leg which is closed at the sides and of ai height equal to the total height of at least' two ovens placed one above the other, combined with heat transmitting' members so arranged as to transmit heat fromthe circulating gas tovb'etween the vertically adjacent ovens.

If the ovens are placed at the side of, the heat generator the air or other gas ascending in' the space between the ovens and the heat generator is cooled by the ovens. This also decreases the draught in the circulation channel. One object of the* invention is to' increasethe circul'ation 55,.

like arranged between the ovens and the heat generator in such a way as to prevent the: circulat'ihg gas( from passing therebetween, while heat is transmi'tted through. radi'ati'on or conduction to the wall's of the ovens which are Situated next to the heat generator.

Other objects of the invention will' be understo'od from the following description and the accompanying drawing, forming. part of this specification, and in which:

Fig. I is a more or less diagrammatic View of one. embodment of\ my invention;

Fig '2` i's a similar View of another embodiment;

Fi'g.. 3"i's a' similar View of'a thi'rd' embodiment; and

Fig 4` is a cross-secti'onal View of' a complete stove showing a. fourth embodiment in my invention. e

Referring more particularly to Fig. I reference' character. l' indicates' the heat generatcr of a; heating app*aratus, provided With two ovens Hand: [4: placed" the one above the other. These ovens as Well as the heat generat'or areenclosed in a closed chamber, containingair, and extend from'. the front' to the rear* wall' of said chamber a; circul'ation channel thus being formed round the two* ovens. 'Ihi's channel' consists of a: vertical"` section IK', one horizontal' section 20', running above* the top oven, another vertical section 22, and' one horizontal section* 24; running below' the bottom" oven.

When. the air in" the channel' section 8' is heated by' the heat generator' I a, an ascending air current is' produced in* this" channel; The air,` contained in the channel .section 22'; is. cooler, and tends' to' flow downwards. For this reason the air in the' circulati'on channel is made to circulate -in' a closed circuit'round' the ovens..

In order to make" sure' that a sufiicientl'y' large quantity' of' heat' is' transmitt'ed: to the; bottom of" the upper' ovenand the roof' of the lower oven, two plates 28' and 363, bent' in angles, are arran'ged between the ovens: The'plates. have vertical'portions` running' parailel with' the; heat' gen'erator, absorbing heat.` fromsame; which is then transmitted to the' ovens' through the horizontal portions'- of" the pl'ates; which are placed' between the* ovens: The plates are made of a metal of high heat' condnctivity', for' instance' alumin'um.

Fig 2* shows an' arrangem'ent', by means of which the increased circul'ation speed is'rea'ched', although there is a channel 26 between the'ovens. The channel ta is in' this case closed at the' oven side through a wall 32, running from the lower oven upwards between the heat generator and the upper oven !4. The wall 32 is situated at some distance from the upper oven !4, so that a vertical channel 34, communicating with channel 26, is formed between these parts. One portion of the ascending air column in the channel !8 continues as usual through the channels 20,

22 and 24, whereas one portion fioWs downwards' through the channel 34 and. further through the channel 26 to the vertical channel 22. This latter air current transmits heat to the bottom and the side of the oven !4, which faces the heat generator, and to the top of the lower oven !2. The side of the oven !2, which faces the heat generator, receives heat mainly through radiaton.

Fig. 3 shows a heating device, the heat generator !0 of which consists of an electric heating element, above which three ovens !2, !4 and !4' are arranged, the one above the other, so that a continuous, vertical channel !8, closed at the sides, is ormed at one side of the ovens, a similar channel 22 being formed at the other side of same. The channels !8 and 22 are connected by means of a channel 20. A wall 32' extends downwardly from the right side wall of the oven !2, so that a chamber is formed, containing the heating element, and at the top communicating with the channel !8. The air column, which is heated in this chamber, fiows upwards through the channel !8, from where it oWs round all ovens and finally returns to the chamber. The air current, circulating in this way, transmits heat from the element to the oven walls, partly directly and partly indirectly through heat conductors 36, which are arranged between the ovens. These heat conductors are provided with flanges 38, by means of which heat is absorbed from the circulating air. The heat, absorbed by the fianges, is conveyed to the roof of the lower oven, the roof and bottom of the middle oven, and to the bottom of the top oven. The other oven walls air surrounding the heating unit then tends to flow upwards, whereas the air in the vertical channel at the right side of the ovens tends to flow downwards. In this way an air current is obtained, moving in a closed circuit passing the heating unit, above the ovens, fiowing downwards at the right side of same and below the ovens. When circulating in this way, the air absorbs heat from the heating unit walls, transmits heat to the top of the upper oven, the right side walls of both ovens and to the bottom of the lower oven.

Heat is transmitted through radiation or con- I duction to the sides of the ovens, which faces are swept by the circuating air and recieve heat directly from same.

With the latter embodiment of the invention continuous Channels !8 and 22, closed at the sides, and of a height equal to the total height of three ovens, are obtained. A substantial pressure, acting in upward direction upon the air column in the channel !8, is produced, so that a rapid circulation, and consequently an efficient transmission of heat takes place.

In Fig. 4 the exterior cover of a stove to which the invention is applied is designated by !!0. The heating unit !!2 is at its top provided with a cooking plate !4, and is connected to a chimney through a fiue !!6. The top part of the heating unit as well as the flue are protected against heat losses by insulation !8. The heating unit extends into a chamber !20, filled with air, and insulated against heat losses, in which two ovens !22 and !24 are placed. The ovens extend from the front side to the rear side of the chamber, so that a circulation channel for the air is formed, in one vertical leg of which the heating unit !2 is located A baflie member !26, also running from the front to the rear side of the air chamber, is arranged between the heating unit and the ovens in such a way as to prevent the air current from ascending between these parts. The air surrounding the heating unit is heated to a high temperature, whereas the air above, below and at the right side of the ovens is cooled by heat transmission to the ovens. The

the heating unit. For this purpose two U-shaped plates !28 and !30, made from a highly heat conductive metal, for instance aluminum, are arranged between the ovens. The left hand ver tical parts of the plates extend parallel to the side wall of the heating unit, from which heat is radiated to the plates. To the bottom of the top oven and to the upper wall of the lower oven heat is conducted through the plates, which also absorb heat from the circulating air through flanges !32 on the right hand parts of the U-shaped plates. The last mentioned parts of the plates !28 and !30 and the parts of same which are situated between the ovens touch the oven walls, whereas the parts of the plates, which face the heating unit, are situated at some distance from the oven walls, so that spaces !34 and !36 are formed between the plates and the ovens. The purpose of these spaces is to prevent the side walls of the ovens, which face the heating unit, from being too highly heated. The spaces !34 and !36 may be filled with insulating material or replaced by an insulating lining on the inner sides of the ovens.

The circulating air is guided by the baffl !26, so as to make it flow round the whole heating unit with the exception of the side of same which faces the oven, and from which heat is radiated to the oven. The heating unit will therefore be uniformly cooled.. As the air current in the ascending part of the circulation channel is not cooled through contact with the oven, it reaches a high temperature. The force acting upon the air column in this part of the channel in upward direction will consequently be strong and a rapid circulation takes place.

The arrangement described above may be varied in many different ways within the scope of the invention. Any kind of baffies may be chosen and inserted in such a way as to prevent the air from passing, to a considerable extent, between the heating unit and the ovens. It is also unessential how many ovens are arranged at the side of the heating unit. It is thus possible to employ one oven only, or more than two ovens. The ovens may also be arranged not only at one side of the heating unit, but also at two opposite sides of same, in which case the baffles direct the air current towards the sides of the heating unit, which do not face the ovens.

In the first place, the invention is intended to be used in connection with stoves, but may also be applied to any kind of heating apparatuses, provided with ovens. In addition to the examples referred to above, even other embodiments of invention may be possible. The air pressure in the circulation channel should preferably be atmospheric, but higher pressure may also be allowed. It is also possible to replace the air by another gas or gas mixture, for instance combustion gases.

What I claim is:

1. In a heating apparatus, a source of heat, a plurality of ovens disposed vertically with respect to each other, means forming a channel for the circulation of fluid in a closed circuit around said ovens and in heat exchange relation with said source of heat, said channel including a vertically extending leg arranged for upward flow therethrough of fluid heated by said source of heat, said leg being 'closed except at the upper and lower ends thereof, and means for conducting heat from the fluid flowing through said leg to top and bottom surfaces of said ovens which are adjacent to each other.

2. In a heating apparatus, a source of heat, a plurality of ovens disposed vertically with respect to each other, means forming a channel for the circulation of fluid in aclosed circuit around said ovens and in heat exchange relation with said source of heat, said channel including a vertically extending leg arranged for upward flow therethrough of fluid heated by said source of heat, said leg being closed except at the upper and lower ends thereof, and a heat conducting element having a portion disposed between and in heat exchange relation with adjacent top and bottom surfaces of said ovens and having another portion formed with heat transfer surface disposed in heat exchange relation with the fluid flowing through said leg.

3. In a heating apparatus, a source of heat, an oven disposed to one side of said source of heat, means forming a channel for the circulation of fluid in a closed circuit around said oven and in heat exchange relation with said source of heat, said channel including a vertically extending leg in heat exchange relation With said source of heat and remote from said oven, and means independent of said fluid for transmitting heat from said source of heat to the side of said oven adjacent to said source.

4. In a heating apparatus, a source of heat, a plurality of ovens disposed vertically with respect to each other, means forming a channel for the circulaton of fluid in a closed circuit around said ovens and in heat exchange relation with said source of heat, said channel including a vertically extending leg in heat exchange relation with said source of heat and remote from said ovens, means independent of said fluid for transmitting heat from'said source of heat to the side of said oven adjacent to said source, and means for preventing the introduction of fluid into said vertical leg at any intermediate point above the lower end thereof.

NILS AUGUST IVAN HALLSTRM. 

